Airfoil or the like for aircraft



July 9 1940 s. GNTER 2,297,402

AIRFOIL ORKTHE LIKE FOR AIRCRAFT Filed Oct. l2, 1938 v 2 Sheets-Sheet 1k" l g July 9, 1946. s. GNTER 2,207,402

AIRFOIL oR THE LIKE FOR AIRCRAFT Filed oct. 12, 193s 2 sheets-sheet 2 ll x l l ll l f l l Patented July 9, 1946 UNTED STATES signor to manyErnst Heinkel, Warnemunde, Ger- Application October 12, 1938, Serial No.234,596

` In Germany June 18, 1937 9 Claims.

This invention relates generally to airfoils and the like for aircraftand in particular to the ailerons and special lift increasing flapsusually fitted thereon:

The generally known special lift increasing flaps of this type which innormal position lie below the trailing edge member of the principal wingand in lift increasing position are extended to the full chord thereofand adapted to be projected rearwardly and deilected downwardly haveproved successful as landing flaps. A drawback however of this specialtype of ap is that hitherto it could not be utilized as an aileron sothat both the special lift increasing ilaps and ailerons had to be tted,and that only a portion of the airfoil benefited by the improvement inthe lift conditions due to the use of said flaps. In the juxtaposedarrangement of such flaps and ailerons there is the further drawbackthat when the ap is fully projected rearwardly the portion of theaileron nearest the flap is located in the ascending current and thiscauses a premature diversion of the flow at the adjacent portion of theaileron of the airfoil. Thus not only the eifect of the aileron but alsothe otherwise attainable maximum lift is reduced.

Lift increasing 'flaps are also known having split ailerons disposedabove them. In this arrangement only decreases in lift can be obtainedby the aid of the upwardly deected aileron; the aileron cannot bedeflected on the other side of the airfoil and the effect of theailerons is therefore very small in such an arrangement.

Ailerons adapted to be used as landing flaps or landing flaps adapted tobe used as ailerons, are also known but in these cases the flaps areinvariably adapted to be swung only around a stationary axis, and assuch to be deected upwardly or downwardly, while owing to the rearwarddisplacement and to the slot covering plate disposed above it andrigidly connected to the airfoil, the lift increasing flaps couldhitherto be used only for downward deection. The great `advantage of t4lift increasing flaps, namely a substantial impr vement of the liftconditions, was lacking in the former landing flaps which could be usedas ailerons...

The invention eliminates all 'the aforesaid drawbacks, as the uppershuttering, the mounting and the actuating devices of the liftincreasing ap are so arranged that the latter can be utilized, not ashitherto only as a landing flap, but also as aileron for upward ordownward deiiections.

The invention consists in an airfoil or the' like having a rearwardlyprojectable flap of the mentioned type arranged below the trailing edgemember thereof, wherein the said flap is upwardly as well as downwardlypivotable for use also as an aileron, both in its retracted and anyprojected position. In this arrangement it is advantageous to have theslot closing plate hinged to the airfoil or airfoil portion infront ofit,v and coupled to the projectable flap or to the device controllingthe said flap, so that when the 10 projected flap is deflected thetrailing edge member of the airfoil moves with the ilap. The couplingbetween the slot closing plate and the flap can be eiected in `a simplemanner, the flap possessing guide rails or other sliding guides uponwhich the rear edge member or other points of the slot closing flap areguided. This coupling may be so designed that the slot between the rearedge member of the closing plate and the upper surface of the landing apvaries when the landing flap is projected according to aerodynamicrequirements.

The essential inventive ingenuity may be expressed by saying either thata lift increasing flap can be utilized in any position as an aileron,thus also for upward deflection, or that the subject matter of theinvention is a rearwardly projectable aileron adapted to be utilizedalso as a landing flap, which in any position, i. e., both whenretracted as well as in any projected position can be deilected upwardlyor downwardly.

Moreover, the invention comprises a particularly suitable method ofcontrolling the mentioned type of flap for use as an aileron. Such flapsare mostly actuated by moving them forwards and backwards by means ofseveral push rods. In many cases curved push rods are utilized, in orderto obtain an enlargement of the angle of attack of the lift increasingflap when projecting it rearwardly. Also in the method of controlaccording to the invention the ap is x'noved by means of push rods, butto these push rods are in addition attached the operating levers foractuating the aileron, so that the said levers are also moved when thementioned flap is being projected. The aileron push rods are thuscoupled to the projecting device. The advantage of this, an advantagenot found in the former control for such a ilap, is that without usingspecial devices the angle of attack ofthis type of flap increases as theflap is projected, which hitherto could be attained4 only by means ofcurved push rods, guide tracksof any desired' kind, arrangements oflevers and the like.

A constructional form of the invention is illustrated dlagrammaticallyby way of example in the drawings wherein:

Figure 1 illustrates an aircraft airfoil with the iiap in the retractedposition.

Figure 2 illustrates the aircraft airfoil with the flap in the projectedposition.

Figure 3 illustrates a suitable constructional form of the control.

A slot closing plate b for the nap c is hinged to the trailing edge ofthe airfoil a. The flap c is adapted to be rearwardly projected by meansof the device d known in connection with lift increasing aps of the typewhich in normal position lies below the trailing edge. The push rod ecauses the upward and downward pivoting of the flap c; in bothillustrations three different positions of the ap c are outlined. On theupper surface it carries guide rails f, upon which the rear end g of theclosing plate b slides by means of rollers. studs or in other mannerknown per se, both when the flap is being deflected and projectedrearwardly. The guide rails f being suitably designed for the purpose,any desired width of slot between the trailing edge member of theairfoil and the flap can be obtained whenever the flap is beingdisplaced whether forwardly or rearwardly or for the purpose of varyingits angle of attack.

In Figure 3 the flap c is drawn in full lines for the high speed flightposition, and in dotted lines for the landing position. The arrangementis shown diagrammatically as seen from above. The displacing motion ofthe projecting push rod d is eiected by means of a rack h attached onthe said push rod d and of a pinion k in engagement with the rack; thepinion k being actuated by means of the pull rope z'. A bell. cranklever Z is pivotally mounted on the projecting push rod d, the aileronactuating rod e being attached to one arm and the rod o leading to theaileron push rod 1iV being attached to the other arm of the said bellcrank lever. The rod e is in the usual manner articulated to a lever armm rigidly attached to the ilap c as illustrated for example in Figures 1and 2.

The operation of the device for actuating the flap c both when acting asa landing flap and as an aileron may easily be gathered from the draw'-ings, as both in the retracted and in projected state several positionsof the aileron bell crank are illustrated. It may further be seen fromthe lower position of the said bell crank l shown in dotted lines inFigure 3, that during its rearward projection the flap c alreadyundergoes a downward deflection inasmuch as when the flap is projectedthe bell crank lever l is in a position different from the position inwhich it is when the flap is retracted.

As will be seen from the illustrations, the ap according to theinvention can be used, in the retracted and in the projected state, bothas an aileron and as a landing ilap. 'I'he advantage of the liftincreasing flap. namely the enlargement of the airfoil area and thusalso of the lift is therefore also obtained by means of the inventionfrom a landing :dap adapted to be used as an aileron.

I claim:

1. An air foil for aircraft comprising a principal wing, a variabletrailing edge member pivotally mounted on said principal'wing, a flaplying in normal position below the said trailing edge member and in liftincreasing position extended to its full chord behind the principalwing, means for extending and retracting the said flap in asubstantially chordwise direction and means adapted to rock the said napabout its axis of suspension. i

2. An airfoil for aircraft comprising a principal wing, a variabletrailing edge member pivotally mounted on said principal wing, a flaplying in normal position below the said trailing edge member and in liftincreasing position extended to its full chord behind the principalwing, guide rails arranged on the said ap and adapted to guide the saidtrailing edge member, and means adapted to rock the said flap about itsaxis of suspension.

3. An airfoil for aircraft .comprising a principal wing, a variabletrailing edge member pivotally mounted on said principal wing, a flaplying in normal position below the said trailing edge member and in liftincreasing position extended to its full chord behind the principalwing, guide rails arranged on the upper. surface of the said flap, meansarranged on the trailing edge member and adapted to connect said edgemember with the guide rails, and means to control the angular movementsof the said flap.

4. An airfoil for aircraft comprising a principal wing, a variabletrailing edge member pivotally mounted on said principal wing, a ilaplying in normal position below the said trailing edge member and in liftincreasing position extended to its full chord behind the principalwing, guide rails arranged on the upper surface of the said flap, meansfor projecting the said flap rearwardly of the said plane and means forrocking the flap in both its retracted and its projected positions.

5. An airfoil for aircraft comprising a principal wing, a variabletrailing edge member pivotally mounted on said principal wing, a iiaplying in normal position below the said trailing edge member and in liftincreasing position extended to its full chord behind the principalwing, guide rails connected to the said flap, means arranged on thetrailing edge member and adapted to couple the trailing edge member withthe said guide rails, driving means to project and to retract the saidflap, and means connected with the driving means for the said flap tocontrol the angular movements of the ap about its axis of suspension.

6. An airfoil for aircraft comprising a princimember and in liftincreasing position extended` to its full chord behind the principalwing, guide rails connected to the said ilap, means arranged on thetrailing edge member and adapted to couple the trailing edge member withthe said guide rails, a push rod for projecting said iiap rearwardly ofthe principal wing, means for actuating the flap in the manner -of anaileron and comprising a bell crank lever pivotally mounted on said pushrod.

7. An airfoil for aircraft according to claim 6. in which one arm of thebell crank lever is connected to the ap and the other arm is connectedto an actuating rod for actuating the nap.

8. An airfoil for aircraft according to claim 6, in which the push rodarranged in the principal wing is provided with a rack adapted to engagewith a pinion.

9. An airfoil for aircraft comprising a principal wing,'a variabletrailing edge member pivotally mounted on said principal wing, a aplying in normal positionbelow the said trailing rearwardly of saidprincipal wing, a rack attached on the said push rod and in engagementedge member and in lift increasing position extended to its full chordbehind the principal wing, guide rails connected to the said ap, meansarranged on the trailing edge member and adapted to couple the trailingedge member with the said guide rails, a push rod for projecting saidflap with a. pinion and means for actuating the said pinion.

SIEGFRIED GN'I'ER.

